When water freezes into ice at 0° C. or less, it swells by about 10%. If a coolant for cooling a heat exchanger such as a car engine freezes like water, a radiator or an engine block gets damaged. For this reason, the coolant for cooling a car engine has been conventionally prevented from freezing by adding a chemical having a low freezing point thereto and then using it after dilution. Such chemical to be added to the coolant contains glycols or alcohols as a main component. Further, in order to prevent metal corrosion and extend the service life of the metal, a rust inhibitor, a corrosion inhibitor, and an antioxidant are added (See “what is claimed is” of Japanese Unexamined Patent Publication No. (Patent Kokai No.) 07-157886 (1995) and “what is claimed is” of Japanese Unexamined Patent Publication No. 2002-97461, for example). Conventionally, a large amount of ethylene glycol has been used as a radiator coolant.
Particularly, in the winter season in a cold district, a passenger or a car slips on the road because the road freezes due to rainfall, snowfall, or frost or snow is trodden down on the road, and thus accidents and traffic jam are caused. In view of smooth traffic flow and transportation and prevention of danger, it is inevitable to take measures to melt snow on the road surface and to prevent freezing of the road surface. Therefore, the central or each local government or road maintenance industry distributes various antifreezing agents over the road surface to prevent freezing of the road surface. Specifically, an antifreezing agent containing sodium chloride and calcium chloride as a main component (See “what is claimed is” of Japanese Unexamined Patent Publication No. 11-061095 (1999), “what is claimed is” of Japanese Unexamined Patent Publication No. 2000-204343, and “what is claimed is” of Japanese Unexamined Patent Publication No. 2002-060726, for example) is distributed over the road. The distributed antifreezing agent melts in water on the road and increases the concentration of salt in the water, thus lowering the freezing temperature of the water. Also, the antifreezing agent melts snow or ice on the road by its own melting heat.
However, considering danger to environment, human body and animals, there has been a growing trend to regulate an additive contained in such antifreezing agent. Examples of substances which are likely to be regulated as harmful air contaminants include: sulfur base additives; chlorine base additives; boron compounds; nitrite and derivatives thereof; formaldehyde and derivatives thereof; amines such as hydroxylamine, diethanolamine, nitrosamines, and triethanolamine; PCP; PCB; other dioxin-containing substances; heavy metals; and ethylene glycol.
The aforementioned prior art antifreeze solution contains the substances described above. For this reason, it has been desired to develop a novel antifreeze solution containing no environmentally harmful substances.
In the meanwhile, an antifreezing agent for preventing the icing of the road surfaces contains chloride. Therefore, such antifreezing agent causes metal components that constitute a car, coating for protecting an electric system, and tires to rust and deteriorate. Further, such antifreezing agent causes the scaling deterioration of concrete or asphalt. When such antifreezing agent melt in water, it contaminates the soil around the road and exerts an adverse effect on living animal and plant life. Considering such effect, some municipalities stop using chloride and use acetic acid instead of chloride. However, since acetic acid is much more expensive than chloride, it is not possible to use a large amount of acetic acid. For this reason, some municipalities blockade the icy road. Therefore, it has been desired to develop a cheap and environmentally friendly antifreezing agent.
As a snow-melting agent for melting snow on the roof or the like, there has been used hot water so far. However, hot water freezes as temperature drops. Therefore, snow cannot often be removed.
As the result of our researches to provide a novel antifreeze solution that can be used as a radiator coolant, antifreezing agent, snow-melting agent, or the like, the inventor of the present invention has eventually found the present invention. The antifreeze solution of the present invention is composed of environmentally friendly and sanitary substances which do not exert an adverse effect on living animal and plant life and which are not legally regulated. The antifreeze solution of the present invention does not cause metals to rust and does not freeze even at law temperature. Further, the antifreeze solution of the present invention is environmentally friendly and does not require any complicated wastewater treatment after use.